Study of the absorption spectra of the 4f electron transitions of the praseodymium complex with ciprofloxacin and its analytical application

Ciprofloxacin (CPFX) is proposed as a reagent for the derivative spectrophotometric determination of praseodymium in mixed rare earths. The absorption spectra of 4f electron transitions of the praseodymium complex with CPFX was studied by normal and derivative spectrophotometry. The stoichiometry of the praseodymium–CPFX complex was calculated by the molar ratio and continuous variations methods. A ratio of Pr to CPFX of 1∶3 was found. The absorption bands of the 4f electron transitions of the complex were enhanced markedly. Using the third derivative spectrum. Beer’s law was obeyed up to 35 μg cm⁻³ of praseodymium. The relative standard deviation is 0.62% for 14 μg cm⁻³ of praseodymium. The detection and quantification limits were 0.17 and 0.56 μg cm⁻³ of praseodymium, respectively. A method for the direct determination of praseodymium in mixtures of rare earths with good accuracy and selectivity is described.